Robot cleaner and control method thereof

1. A robot cleaner comprising: a bumper sensor to detect a collision with an obstacle; a driving part for moving the robot cleaner in a proceeding travel direction; and a controller that drives the driving part to move the robot cleaner by a predetermined distance in an opposite direction to the proceeding travel direction thereof when the bumper sensor detects the collision with the obstacle, that determines whether the robot cleaner is moving in the opposite direction by the predetermined distance, that determines whether the bumper sensor is off or on after the robot cleaner moved in the opposite direction by the predetermined distance, that after determining that the bumper sensor is on after the robot cleaner moved in the opposite direction by the predetermined distance, repeats driving the driving part again to move the robot cleaner in the opposite direction by the predetermined distance to a current position of the robot cleaner and determining whether the bumper sensor is off, and that measures the number of times in which the robot cleaner repeats moving in the opposite direction in real-time and compares the measured number with a predetermined reference number, wherein the controller determines that the bumper sensor is broken and stops the driving part when the measured number is more than the reference number.

2. The robot cleaner of claim 1 , wherein the controller is connected to a sound unit and a display unit, and the controller activates at least one of the sound unit and display unit when the measured number is more than the reference number.

3. The robot cleaner of claim 2 , wherein the sound unit is a speaker and the display unit is a monitor.

4. The robot cleaner of claim 2 , further comprising a dust collecting part disposed in a body of the robot cleaner.

5. The robot cleaner of claim 4 , wherein the driving part includes at least two wheels.

6. The robot cleaner of claim 1 , wherein the reference number comprises at least three times.

7. A method for controlling a robot cleaner, comprising: driving a driving part of the robot cleaner in a proceeding travel direction along a surface to be cleaned; driving the driving part to move the robot cleaner by a predetermined distance in an opposite direction to the proceeding travel direction thereof when a bumper sensor of the robot cleaner detects a collision with an obstacle; determining whether the robot cleaner moves in the opposite direction by the predetermined distance; determining whether the bumper sensor is off or on after the robot cleaner moved in the opposite direction by the predetermined distance; driving the driving part again to move the robot cleaner in the opposite direction by the predetermined distance after determining that the bumper sensor is on after the robot cleaner moved in the opposite direction by the predetermined distance, and measuring the number of times the robot cleaner repeats moving in real-time in the opposite direction away from the obstacle; comparing the measured number with a predetermined reference number; and determining that the bumper sensor is broken and stopping the driving part when the measured number is greater than the reference number.

8. The method of claim 7 , further comprising: informing a user of a breakdown diagnosis to the bumper sensor after stopping the driving part.

9. The method of claim 8 , further comprising the step of activating a sound unit or a display unit to inform the user of the breakdown diagnosis.

10. The method of claim 7 , further comprising the step of directly inputting the reference number into a controller.

11. The method of claim 10 , wherein the reference number comprises at least three times.